Solid-state image sensing device such as CCD image sensors and CMOS image sensors are used for various purposes in, for example, digital still cameras, video cameras, or surveillance cameras.
A back-side illumination image sensor can eliminate an obstacle to light such as interconnection between pixels and a microlens. Therefore, the back-side illumination image sensor permits higher pixel sensitivity to incident light and lower optical shading.
Accordingly, the development of the back-side illumination image sensors has been carried on in recent years.